1. Field of the Invention
The present invention relates generally to structures and assemblies for use in connection with a patient interface device, and, in particular, to a forehead pad and forehead support assembly for use in connection with a patient interface device that provides additional comfort to the patient.
2. Description of the Related Art
There are numerous situations where it is necessary or desirable to deliver a flow of breathing gas, non-invasively, to the airway of a patient, i.e., without intubating the patient or surgically inserting a tracheotomy tube in their trachea. For example, it is known to ventilate a patient using a technique known as non-invasive ventilation (NIV). It is also known to deliver continuous positive airway pressure (CPAP) or variable airway pressure, which varies with the patient's respiratory cycle or a monitored condition of the patient, to treat a medical disorder, such as sleep apnea syndrome, in particular, obstructive sleep apnea (OSA), congestive heart failure, stroke, Cheynes-Stokes respiration, etc. Non-invasive ventilation and pressure support therapies involve the placement of a patient interface device, which is typically a nasal or nasal/oral mask, on the face of a patient to interface the ventilator or pressure support device with the airway of the patient, so that a flow of breathing gas can be delivered from the pressure/flow generating device to the airway of the patient.
Patients suffering from a pulmonary or respiratory disorder, such as obstructive sleep apnea, are often treated with a pressure support device, such as a CPAP device. A CPAP device delivers a flow of fluid to the airway of the patient throughout the patient's breathing cycle in order to “splint” the airway, thereby preventing its collapse during sleep. In another type of treatment, bi-level positive pressure therapy is provided to the patient, in which the pressure of air delivered to the patient's airway varies or is synchronized with the patient's breathing cycle to maximize therapeutic effect and comfort to the patient. A pressure support device may also provide “bi-level” pressure support, in which a lower pressure is delivered to that patient during the patient's expiratory phase then during the inspiratory phase.
It is also known to provide an auto-titration positive pressure therapy in which the pressure provided to the patient changes based upon the detected conditions of the patient, such as whether the patient is snoring or experiencing an apnea, hypopnea, or upper airway resistance. Such a device adjusts the pressure delivered to the patient, based on whether or not the patient is snoring. For example, a pressure support device may actively test the patient's airway to determine whether obstruction, complete or partial, could occur and adjust the pressure output to avoid this result.
Other modes of providing positive pressure support to a patient are known. For example, a proportional assist ventilation mode of pressure support provides a positive pressure therapy in which the pressure of gas delivered to the patient varies with the patient's breathing effort to increase the comfort of the patient. Proportional positive airway pressure (PPAP) devices deliver breathing gas to the patient based on the flow generated by the patient.
For purposes of the present invention, the phrase “pressure support system”, “pressure support device”, or “positive pressure support” includes any medical device or method that delivers a flow of breathing gas to the airway of a patient, including a ventilator, CPAP, bi-level, PAV, PPAP, or bi-level pressure support system.
Because such patient interface devices are typically worn for an extended period of time, a variety of concerns must be taken into consideration. For example, in providing CPAP or other positive pressure therapy to treat OSA, the patient normally wears the patient interface device all night long while he or she sleeps. One concern in such a situation is that the patient interface device is as comfortable as possible, otherwise the patient may avoid wearing the interface device, defeating the purpose of the prescribed pressure support therapy.
In order to provide gas or, as discussed above, oxygen, to a patient, the patient must use a patient interface device, such as a respiratory mask, as known in the art. These respiratory masks are provided in many variations, such as nasal masks, nasal and oral masks, mouth masks, full-face masks, etc. All of these mask devices are used to provide oxygen or air to the patient. Typically, the gas stream is extracted from a pressure generating device, such as those devices discussed above, which may be, in turn, in fluid communication with an oxygen tank. The oxygen flows from the source through the regulator devices, through the pressure generating device and further through a conduit into the mask. The pressure generating device and the conduit, such as a gas hose, are considered the patient circuit, such that a coupling assembly is required for connecting the patient circuit to the patient interface device.
In a conventional pressure support system, a flexible conduit is coupled to an exit conduit. The flexible conduit forms part of the patient circuit that carries the flow of breathing gas from the pressure generating system to the patient interface device. In a support system, the patient interface device connects the patient circuit with the airway of the patient so that the elevated pressure gas flow is delivered to the patient's airway. Examples of patient interface devices include a nasal mask, nasal and oral mask, full-face mask, nasal cannula, oral mouthpiece, tracheal tube, endotracheal tube, or hood.
It is known in the art to provide forehead support assemblies associated with gas delivery masks to provide a support mechanism between the mask and the patient's forehead. Gas delivery masks having forehead cushions, spacers or supports are described in U.S. Pat. Nos. 4,907,584; 5,243,971; 5,570,689; 6,119,693; 6,357,441; 6,463,931; 6,467,483; 6,520,182; 6,532,961; and 6,557,556. The forehead support assemblies and associated structures and members serve to prevent the mask from exerting additional and unrequired force on a patient's face, and further provide stability to the mask when attached to the patient.
For example, in U.S. Pat. No. 6,557,556 (“the '556 patent”) discloses a forehead support for facial mask that includes multiple pads that provide the contact points on the user for the forehead support. In addition, these pads include an inner cavity of annular interior with two retaining walls. These retaining walls provide structural integrity to the pads, and limit deformation of these pads.
The forehead support assemblies disclosed in the above-referenced patents typically have at least one forehead pad attached to the forehead support member. The forehead pad contacts the surface of the forehead of the patient. In U.S. Pat. Nos. 4,907,584; 5,243,971; 5,517,986; 5,570,689; and 6,357,441, the forehead support pads are typically formed from a foam material and generally have a rectangular or trapezoidal shape with relatively sharp edges. The conventional forehead pads taught in U.S. Pat. Nos. 6,119,693; 6,463,931; 6,467,483; 6,520,182; 6,532,961; and 6,557,556 have a semi-circular profile to compensate for any angular variation between the forehead support assembly structure and the surface of the patient's forehead. The disadvantage of such a design is that the forehead pad rests on the forehead on a curved surface, which translates into an undesirable pressure point. These semi-circular designs allow the curved contact to compress and deform to secure a flatter contact area. However, this also creates pressure points and illustrates a less comfortable option.
The product literature for the MAP Papillon mask discloses a forehead pad that attaches to the forehead support member via a stem. The stem and/or the attachment of the stem to the forehead support frame allow for some articulation of the main portion of the forehead pad. However, the relatively small size of the stem provides a relatively unstable platform for mounting the forehead pad on the support frame or forehead support member.